We propose to investigate the sources of variation affecting the quantity of saliva-secreted by mosquitoes, and shall identify the varius functions of saliva in blood- and sugar-feeding. Toward these ends, we have developed microscopical procedures and fluorescent tracer system for labeling saliva. We shall determine the quantity of saliva delivered through the mouthparts and measure the volume that different parts of the salivary apparatus contribute to collect and measure the volume of saliva produced. Humoral and neural control of salivation will be studied in order to identify psysiological mechanisms linking external stimuli with salivation. Using vital dyes, we propose to trace neural pathways and individual neurons innervating the salivary pump and glands. Electrophysiological techniques will complement these studies. In studies designed to identify humoral control of salivation, we shall determine whether humoral factors regulate salivary output. The time course of release of malaria sporozoites will be determined. It is anticipated that this work will contribute to an understanding of the physiology of salivation of arthropods of medical importance.